Conventional heald shaft couplings comprise one or several elements that form a first or shaft section of the coupling and one or more elements forming a second or drive section of the respective coupling. The sections engage each other in the coupled state in a positive manner also referred to as a "form-locking" manner which transmits the drive power between the corresponding heald shaft drive and the respective heald shaft.
Conventional heald shaft couplings require involved tools for the coupling and decoupling of the heald shafts from or with the respective heald drive. These tools are used to individually connect or disconnect each coupling which is very time consuming. As a result, the coupling of the harness with its many heald shafts to the shaft drives requires a substantial amount of time for a harness exchange.
Efforts have been made heretofore to reduce the time required for a harness exchange. Reference is made to European Patent Publication EP 0,407,335 (Peter) disclosing a loom with a tiltable operating tool for the heald shaft couplings. Such a tool enables the simultaneous connecting and disconnecting or opening and closing of a plurality of heald shaft couplings. The operation of the conventional tool requires two conditions that must be met. First, the heald shaft couplings require a special construction. Second, the heald shafts must first be brought into the so-called equal shaft position. The tool itself is fixed to the machine frame. The tool reaches around individual shaft couplings or around the total number of shaft couplings. After the tool has been adjusted by rotating the tool, a tension force is applied to the drive connected sections of the heald shaft couplings, whereby these couplings are simultaneously either coupled or decoupled.
Conventional heald shaft couplings of the type just described require a relatively large effort and expense, especially in their manufacture, because the drive sections and the shaft sections of a coupling have an involved geometric configuration as well as a multitude of cooperating surfaces for the transmission of tension and impact forces.